| 摘要 |
PURPOSE:To align masks and wafers accurately at a high speed by obtaining a plurality of different detected images by introducing incident light from a plurality of different angles, combining the detected images and aligning them. CONSTITUTION:Laser emitting units 1, 17 are controlled by a laser controller 3 via control lines 5a, 5b to switch the incident angle of emitting light source. The light emitted from the unit 1 passes a beam splitter 2, then passes a window 27 on a mask 12 through a lens 11 to become a light trace 8'' to be emitted on the alignment pattern 24 on a wafer 13. The traces 8' and 3'' of the light are emitted in the same pattern but are emitted at different incident angles. Thus, the images detected by a photodetector 12 are different. A photodetected image combining unit 4 combined the images of two types, and aligned by the optimized imaged. The quantities of light of the units 1, 17 are controlled by the laser controller to be detected by photodetectors 5A, 5B. The levels of the reflected lights are controlled to become near values. |
